There are a couple of things to consider before setting your homeschool schedule: 1) when do your children learn best, morning or afternoon -- you may not be able to determine this until trying one or the other and seeing how well it works; 2) what is your husband's work schedule -- if he works a shift that requires him to sleep during the day, you may need to figure out how to school around that, or if he works a shift where he is only home a few hours during the children's awake time, you may want to be sure to spend that time with him and have him be involved and then do other studies while he is working; 3) consider yourself, allow flexibility for unexpected events or emergencies to avoid being stressed when deadlines loom and you haven't finished schooling yet.
That being said, I'll explain my choice of schedule to give you an example and give a few other options. My husband works during the day and is home evenings and weekends and I like to get work done in the mornings and have the rest of the day to enjoy and do what I enjoy, therefore, I trained my children that way as well, because I found that if I allowed any play time before school work was complete, they had a hard time getting back to school work. Therefore, our rule became "schoolwork right after breakfast until it is finished, although we take lunch when it is lunchtime. Then when schoolwork is finished, the rest of the day is your time to do what you want." This has worked very well and most days, we are finished with school by lunchtime, although sometimes we need to finish after lunch. We hardly ever go past 2 p.m.
We begin school every year in July, the week after Fourth of July week and we end by the end of the first or second week of May. That gives us a full two months off, and we have found that if we take any longer than that, the boys become bored and start asking to start school. We also take at least one full week, but usually try to take two full weeks, off at Christmas. I like to take the week before to be able to decorate, bake and shop without getting stressed by trying to fit school in too, and then the boys like the week after so that they can enjoy their new gifts for a while before having to get back to the schoolwork. We really like this schedule because it still gives us enough flexibility so that if an emergency or unexpected situation happens at any other time of the year, we can take a day off here or there without having to stress about it.
We don't always take a family vacation, but if we do, we do several things that can be counted for school so that we can keep our schedule. By this, I don't mean that we make the boys "crack the books" on vacation; what I mean is we visit something educational such as a museum or a zoo -- something that is fun but where they are also learning something about history or science.
I know lots of people who still choose to take the entire summer off and follow a schedule like the public school. I also know people who homeschool all year round and simply take breaks throughout the year like a Spring break, a Fall break, a Winter break and a Summer break. It all depends upon what works for you. Plan your schedule according to what you find works best for your family and creates the least amount of stress for you and your family, and that will help you to be able to continue your homeschool journey year after year. It helps avoid burnout.